Mobile carriage

ABSTRACT

A mobile carriage system includes a pair of end rails (12a, 12c) fixed to a support surface and one or more intermediate rails (12b) located parallel to and between the pair of end rails (12a, 12c). At least one carriage (10) is supported for movement on the end and intermediate rails (12a-c). The carriage (10) includes an elongated frame (17) that spans all of the rails. At least two drive units, each including a pair of wheels (23) and supporting the carriage on a different one of the rails are provided. The drive units are operatively connected to a drive shaft (35) which extends across a plurality of the rails. The drive shaft (35) and each of the drive units are coupled by a drive gear (33) on the shaft which has a substantially smaller diameter than the diameter of driven gears (29) on the units. An electric motor (41) is operatively connected to the drive shaft (35).

BACKGROUND OF THE INVENTION

This invention pertains to power transmission, and more particularly toapparatus for driving mobile storage carriages.

Mobile storage systems, for storing books, supplies, and files are inwidespread use where it is important to provide high density storage,such as in offices, schools, and libraries. My U.S. Pat. No. 5,007,351describes an improved power transmission mechanism for use in suchsystems.

Typical mobile storage systems include two or more parallel railsembedded in or attached to a building floor. One or more relatively longand narrow carriages span the rails. The carriages may exceed eightyfeet in length, and the number and spacing of the rails are chosen tosuit the particular carriage length. The carriages are usually supportedby a pair of wheels rolling along each of the rails.

The carriages may be designed to move along the rails under manualpower. For that purpose, a hand wheel is usually mounted to a carriageend panel. The hand wheel is connected by various drive components to ashaft that in turn is connected with at least one of the carriagewheels. Manually rotating the hand wheel causes the drive wheels torotate and move the carriage. Electrically powered carriages are also inwide-spread use. With that design, a suitable electric motor issubstituted for the manual hand wheel. The motor shaft is mechanicallyconnected through a suitable mechanism to the carriage drive wheels.

It has been a common practice to design mobile carriages such that drivewheels are located along the length of the carriage on one side of thecarriage. These prior designs require a long shaft for connecting thedrive wheels along the carriage length. The long shafts are awkward toassemble and service. In addition, the long shafts generally undergotorsional wind-up when used with heavy carriages, such that, due totwisting of the shaft along its length, the drive wheels at the carriageend remote from the electric motor or hand wheel do not rotate as fastas the drive wheels at the end at which the shaft is rotationallydriven. Consequently, despite the use of flanges on the drive wheels,the carriages can tend to skew as they are driven along the rails.

In accordance with my earlier patent, a single driving mechanism wasprovided at the center of the carriage. However, a need has continued toexist for improved mobile storage carriages with more than one drivemechanism, but which would overcome the aforementioned skewing problemencountered with the prior art.

SUMMARY OF THE INVENTION

In accordance with the present invention, drive systems are providedwhich improve the performance of mobile storage system carriages andwhich obviate the aforementioned skewing problem.

In accordance with the invention, at least two synchronized transverselyspaced drive units each engage separate rails. A single power sourcesuch as an electric motor is connected to a drive shaft that spans allof the rails on which drive units are provided. The shaft is providedwith drive sprockets which are intermeshed with driven gears of thedrive mechanisms. Torsional twisting of the drive shaft is minimized byuse of gear ratios between these gears which provide a sufficientmechanical advantage to effectively reduce the torque applied to thedrive shaft.

As in the case of my earlier invention, the drive wheels may havecentral flanges that fit within and are guided by a longitudinal groovein the rail top surface. Alternatively, the wheels may be flat or may beprovided with flanges on each side and are adapted to travel on a flatrail. Anti-tip restraining clips may be provided to insure stability ofthe mobile storage system.

To drive the carriage drive wheels of each drive unit insynchronization, sprockets are provided to which power is transferred bymeans of a chain trained around the sprockets. The chain is driven by adrive sprocket that is attached to the drive shaft, which is in turnrotated by a power source such as an electric motor or the output shaftof a speed reducer. To provide tension adjustment to the drive chain,the drive sprocket or a separate idler sprocket is preferably madeadjustable. The drive units of the present invention may also be drivenby manually powered mechanisms.

Briefly, a mobile carriage system of this invention includes a pair ofspaced, parallel end rails fixed to a support surface, and, usually,dependent on the length of the carriage, at least one or moreintermediate rails fixed to the support surface and located parallel toand between the pair of end rails. At least one carriage is supportedfor movement on the end and any intermediate rails. The carriageincludes an elongated frame that spans all of the rails. At least twodrive units, each including a pair of wheels and supporting the carriageon a different one of the rails are provided. The drive units areoperatively connected to a drive shaft which extends across a pluralityof the rails. The drive shaft and each of the drive units are coupled bya drive gear on the shaft which has a first effective diameter and adriven gear on the drive unit, which has a second effective diametersubstantially greater than the first effective diameter. Thus, the driveunits minimize torsional twisting of the drive shaft during use. Asource of rotational power such as an electric motor is operativelyconnected to the drive shaft.

Other features of the present invention will become apparent from theclaims, detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified side view of a mobile storage carriage thatemploys the present invention;

FIG. 2 is a cross sectional view taken along lines 2--2 of FIG. 1 androtated 90° counterclockwise,

FIG. 3 a cross sectional view of another embodiment of the inventiontaken along lines 2--2 of FIG. 1 and rotated 90° counterclockwise;

FIG. 4 is a view similar to those of FIGS. 2 and 3 showing a prior artdevice;

FIG. 5 is an exploded partially broken perspective view of anelectrically powered drive mechanism according to the present invention;

FIG. 6 is a fragmentary sectional view taken along Line of 6--6 of FIG.5; and

FIGS. 7 and 8 are fragmentary sectional views similar to that of FIG. 6showing alternate embodiments of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a mobile storage carriage 10 is illustrated thatincludes the present invention. The mobile carriage 10 is typically partof a mobile storage system that includes additional mobile carriages, aswell as one or more stationary storage units (not shown), as are knownin the art.

The mobile carriage 10 travels along two or more parallel rails 12spaced longitudinally along the carriage length and embedded in orattached to a building floor 9. The carriage is supported on the rails12 by respective pairs of wheels 11. Power for moving the carriage alongthe rails may be supplied manually. In that case, the ends of thecarriage are usually furnished with a hand wheel 13. Alternately, thecarriage may be designed with an electrically powered system. In thatsituation, the hand wheel 13 is eliminated, and a suitable electricalcontrol, schematically represented at reference numeral 15, issubstituted.

In accordance with the present invention, electrically and manuallypowered mobile carriages are driven along at least two of the rails 12aand 12c by synchronized pairs of wheels wherein each pair engages arail. Looking also at FIG. 2, a mobile storage system is depicted thathas three rails 12a, 12b and 12c. The frame 17 of a carriage 10 isdesigned with longitudinal beams 19 and with end members 20 at oppositeends and a cross brace structural member 21 adjacent to each of therails. At least two wheels 11 are suitably journaled in each cross brace21 for supporting the carriage on each associated rail which is notprovided with drive wheels. The mounting of the wheels to the crossbraces may be by conventional components that do not form a part of thepresent invention.

The present invention overcomes the skewing problem illustrated in FIG.4, which somewhat diagrammatically illustrates the prior art devices. InFIG. 4 there are seen a plurality of rails R. Rails R support a mobilecarriage which is supported on a frame F. Frame F is rollingly supportedon rails R by means of drive wheels W. Drive wheels W are powered by amotor M using a drive shaft S. As seen in FIG. 4, the wheels closest tomotor M are imparted with greater turning motion, thus skewing thecarriage as shown. The declining amount of forward movement of thewheels W as they are spaced away from motor M is caused by the fact thata substantial amount of torque needs to be applied by motor M throughdrive shaft S. This amount of torque causes rotational twisting of thedrive shaft S resulting in a lesser amount of rotation of the end of thedrive shaft opposite the motor M.

To drive the carriage 10 along the rails 12a and 12c, the carriage frame17 comprises a plurality, preferably two, pairs of drive wheels 23.Referring also to FIG. 5, the drive wheels 23 are rotatably mounted,usually by bearings, on respective axles 25. The axles 25 are supportedbetween two channels 21 that span the frame longitudinal beams 19, or byend frame 20 and a channel 21. To each drive wheel is attached asprocket 29, for example, by plug welds 30.

Trained over the sprockets 29 is a chain 31. The chain 31 is driven by adrive sprocket 33 which is fastened to a drive shaft 35 of a combinationelectrical motor and speed reducer 41. The motor and speed reducercombination 41 is mounted to the end frame member 20 by conventionalfasteners. Drive sprocket 33 is of a substantially smaller effectivediameter than driven sprockets 29. Thus, a substantially lessertorsional force is developed on drive shaft 35, relative to that of theprior art. To provide adjustability to the chain 31, adjusting screw 45coacts between a flange 47 attached to end frame member 20 and an idlersprocket 49 which serves to adjust the tension on chain 31.

Actuation of the control 15 energizes the motor 41 to rotate the drivewheels 23 in synchronization and move the carriage 10 along the rails12a, 12b and 12c. Appropriate controls are provided to start thecarriage moving in either direction, and to stop the carriage at adesired location along the rails.

FIGS. 6-8 show three alternate embodiments of structures provided toguide the carriage 10 along the rails 12a, 12b and 12c. In theembodiment of FIG. 6 each drive wheel 23 is formed with an annularflange 49 that extends concentrically from the wheel peripheral bearingsurface 50. The drive wheel flanges 49 interfit within grooves 51 formedin the top surface of the rail 12a. In FIG. 6, reference numeral 52represents decorative or safety floor panels placed between the rails,as is known in the art.

Turning to FIG. 7, an alternative version of a wheel and railconfiguration usable in conjunction with the present invention isillustrated. In FIG. 7 there is seen an alternative form of supportingrail 54 which has a T-shaped upper supporting surface 55. A wheel 56having a flat outer perimeter 57 supports the carriage 19 for rollingmovement along rail 55. In order to prevent tipping of the carriage, itis preferred that clips 58 be attached as illustrated to cross framemembers 20 and 21. It will be noted that the clips 58, which engage theupper T-shaped portion of rail 54, thus effectively prevent tipping ofthe carriage.

A still further embodiment of a wheel and rail configuration isillustrated in FIG. 8. In FIG. 8 an alternative rail 60 is of a squareor rectangular cross-section. Rail 60 rollingly supports wheels 61 whichare provided with a central flat surface 62 and side flanges 63 alongeach side thereof which extend outwardly from each side of the flatsupporting surface 62 which rides along rail 60. Flanges 63 thuseffectively keep the wheel 61 rolling along rail 60 as in the case ofthe flange 49 in the embodiment of FIG. 6. In order to provide ananti-tip mechanism for the version shown in FIG. 8, a generally C-shapedchannel 64 is provided under rail 60. Inwardly extending ends 66 ofchannel 64 house downwardly extending clips 67 which, as shown, areaffixed to cross frame members 21. Thus, tipping of the carriagesupported on frame 19 is effectively prevented.

Referring to FIG. 3, an alternate embodiment of an electrically poweredmobile carriage is illustrated. In this embodiment five rails 80a-80esupport a carriage frame 81. Non-powered supporting wheels 11 rollinglysupport the carriage 81 for movement along the associated rails 80a, 80cand 80e. Driven, synchronously powered pairs of wheels 23 are providedon at least two of the rails, in the illustrated embodiment, rails 80band 80d. These wheels are driven by drive shaft 35 which is powered bymotor/speed reducer 41. The remaining components of the design of FIGS.3, including the drive wheels 23 and sprockets 29, etc., are the same asfor the design described previously.

A manually powered mobile carriage, the specific details of which aredescribed in my above-noted issued '351 patent may also be used as analternate construction.

Thus, it is apparent that there has been provided, in accordance withthe invention, mobile carriage that fully satisfies the aims andadvantages set forth above. While the invention has been described inconjunction with specific embodiments thereof, it is evident that manyalternatives, modifications, and variations will be apparent to thoseskilled in the art in light of the foregoing description. Accordingly,it is intended to embrace all such alternatives, modifications andvariations as fall within the spirit and broad scope of the appendedclaims.

What is claimed is:
 1. A mobile storage system, comprising:a series ofsubstantially parallel rails including a first end rail, a second endrail, and a series of intermediate rails located between the first andsecond end rails; a frame spanning across the rails and adapted tosupport one or more storage units; a series of mobile supportsinterconnected with the frame, wherein each mobile support is engageablewith one of the rails for movably supporting the frame on the rail; anda drive arrangement, comprising a power source, a drive shaft driven bythe power source, and a pair of drive units drivingly interconnectedwith the drive shaft, wherein each drive unit is engaged with one of themobile supports inwardly of one of the first and second end rails. 2.The mobile storage system of claim 1, wherein one or more of theintermediate rails are located between the rails with which the driveunits are engaged, wherein the drive shaft spans across the intermediaterails.
 3. The mobile storage system of claim 2, wherein the pair ofdrive units are engaged with the mobile supports at a pair of spacedlocations arranged symmetrically relative to a center of the frame. 4.The mobile storage system of claim 1, wherein the drive shaft and eachdrive unit are coupled by a drive gear on the drive shaft having a firsteffective diameter and a driven gear on the drive unit having a secondeffective diameter substantially greater than the first effectivediameter, wherein the drive units are operated in response to rotationof the drive shaft while minimizing torsional twisting of the driveshaft.
 5. The mobile storage system of claim 3, further comprising apair of sprockets attached to the drive shaft, wherein each sprocket isengaged with a drive chain forming a part of the drive unit.
 6. Themobile storage system of claim 4, wherein each drive unit includes apair of wheels engageable with one of the rails, and wherein the drivechain is drivingly engaged with each of the wheels for impartingmovement to the wheels in response to rotation of the drive shaft.
 7. Amethod of driving a carriage for a mobile storage system which includesa series of substantially parallel rails including a first end rail, asecond end rail, and a series of intermediate rails located between thefirst and second end rails, and wherein the carriage includes a framespanning across the rails and adapted to support one or more storageunits, and a series of mobile supports interconnected with the frame,wherein each mobile support is engageable with one of the rails formovably supporting the frame on the rail, comprising the step of drivingthe carriage on the rails by operation of a pair of drive units, whereineach drive unit is drivingly engaged with one of the mobile supportslocated inwardly of one of the first and second end rails, wherein thepair of drive units are located so as to be symmetrical relative to acenter of the frame, to reduce skewing of the carriage upon operation ofthe drive units.